Another factor to consider is that getting your commission deferred to attend med school after attending USNA is a *huge* hurdle as they are difficult to obtain. My DD, an Army nurse, had a high school classmate that went to USNA and she actually received a deferment to attend med school but the Navy spent so long making a decision that she didn't get into med school. She ended up taking her commission with the Marines and after she does her 5 years, she plans on re-applying to med school.
USNA midshipmen attending medical school commission with their class as Navy Ensigns. If they attend USUHS for medical school, they are in AD status, with full pay and allowances. If they attend a civilian medical school, they are in a Reserve status, receiving a stipend, with med school paid for. Commissions are not deferred. They put on Ensign same day as classmates.
Mids who are interested in this track self-identify early on. There are briefings. There are faculty mentors. There is a USNA selection board that meets to interview and select the mids who will be approved for Med Corps commission. I used to sit on that board as the Dant's rep, in early fall of 1/C (senior) year. I think it now meets second semester 2/C (junior) year. MCAT scores, class standing, GPA, performance in certain courses, motivation, overall record in all areas, were considered. It is usually known by end of junior year which mids are greenlighted for application. This timing allows the mids to know if they can proceed with med school applications.
It is up to the mid to get accepted by a medical school. If they are not, they don't go. Some get accepted, then change their minds and decide to go warfare after all. Mids have usually had no difficulty getting accepted by USUHS, because their USNA background is so compatible and well-known.
Occasionally, commission status can be in jeopardy because of pre-Comm physical DQ issues - it's like DODMERB, Round 2. That can leave some mids hanging with regard to if they will be able to commission (they might be allowed to graduate with degree but not enter service), due to a physical factor. Or their options for warfare communities might be limited. I just mention this because sometimes these issues can drag out while determinations are being made.